ENVISION I Microcosm ADD I 3.0 um prokaryotes

The study was conducted in February 2016 in Vigo (Spain) during one of three cruises. We carried out onboard mesocosm experiments with relevant vitamin additions to study the influence of B-vitamins and inorganic nutrients on bacterioplankton gene expression.Our general hypothesis is that the availability of B-vitamins influences the abundance,distribution, and activity of microbial plankton in coastal waters of the North-East Atlanticocean over short-term and seasonal scales. ENVISION aims at examining for the first time the dynamics of B-vitamins and their role in microbial plankton dynamics at adequate spatial and temporal scales in a highly productive region. We followed a multidisciplinary approach including correlation analysis based on physical, chemical and biological field observations; micro- and mesocosm experiments; and more sophisticated molecular tools such as metatranscriptomic and microautoradiographic analyses to reach the following objectives: (1) To describe the spatial and temporal variability of dissolved B-vitamins (B1, B2, B6, B7, and B12) concentrations in relation to the phytoplankton and bacterioplankton community composition in coastal waters off NW Spain; (2) To assess the spatial and temporal variability of the response of phytoplankton and bacterioplankton to the experimental amendment of mineral nutrients, vitamin B1 and B12 (separately and in combination) in coastal waters off NW Spain; (3) To study the influence of short-term variability in B-vitamins availability on the succession of microbial plankton species; (4) To identify the bacterial groups responsible for B-vitamins synthesis in coastal waters off NW Spain; and (5) To determine the role of bacteria as consumers of B1 and B12 vitamins.